how can i catch 2 computers to show on 1 monitor?

Answer:

Go to your local computer store and buy a KVM. It's a switch that allows you to connect two pc's to one monitor, kb, and mouse.



If you designed at the same time? The single way I know would be to use a gridiron and remote desktop.
You can buy a KVM switch which will allow you to share the monitor, keyboard and mouse for 2 or more desktops.

If your computers are network, you could then install VNC server on one contraption and VNC client on the machine next to the monitor, kybd and mouse. That way you could access the desktop of the other computer.